travis: Add 64-bit to Android build
travis: Add 64-bit to Android build

This is done as a parallel build, so should not impact wait time.

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers